Having shot both of these weapons for many years, I do agree that the Mini is not as accurate as the current crop of AR's. The Mini shoots with about the same accuracy as the old light M16A1 barrel. The A2 and HBar type are much better.
The Mini-14 is a very rugged, reliable firearm. It will function with little or no cleaning or lubrication far beyond what you can expect from the AR-15/M16. For a "store away for a rainy day" or "behind the seat in my pickup" gun, a Mini-14 stainless with synthetic stock is a good choice.
But, most AR's today, with the heavier barrels, really blow the old "bolt actions are more accurate than autos" BS.
The thing that really tips the scales more that any other... Ruger is very tight with parts, insisting you ship them the rifle for factory replacement of many of the parts we would like to keep as spares. This is intolerable.
The fantastic array of good quality parts, easily available, as well as magazines and other accessories, make the AR-15 the only serious choice here.